The effects of the Eurasian beaver (Castor fiber) on hydrology in UK headwater streams

欧亚海狸（蓖麻纤维）是第一种被重新引入英国的哺乳动物，于2016年在苏格兰获得本土地位。海狸是众所周知的栖息地工程师，可以大大改变河流水文。海狸坝减缓水流速度，使其通过各种流动路径，从而增加地表水储存，在某些情况下，可能改变地表-地下水交换，从而影响邻近洪泛区的当地地下水位。其他影响可能包括下游峰值流量减少和基流增加。这些过程在更大的空间尺度（如流域尺度）上的重要性在很大程度上还没有得到理解。此外，英国海狸数量的不断增加意味着河流管理者需要针对海狸水坝造成的水文变化制定基于证据的管理策略。本论文的主要目的是推进海狸坝如何影响河流流量和水文相邻的洪泛区的尺度范围从一个单独的比弗坝到一个小流域（2.2平方公里）的理解。以下研究问题将被解决：研究问题1：海狸坝对水位和河流流量有什么影响，从一个单独的比弗坝的规模到一个小集水区？研究问题2：从单个比弗坝的规模到集水区的规模，海狸坝对邻近洪泛区的水文有什么影响？研究问题3：池塘平整器是否可以成为一种有效的工具，以达到一个妥协的水位，这是足够的海狸，也减少了海狸池塘对农业使用的邻近洪泛区的影响？

The Eurasian beaver (Castor fiber) is the first mammal to be reintroduced to the UK, gaining native status in Scotland in 2016. Beavers are habitat engineers known to substantially alter river hydrology. Beaver dams slow water and route it through a variety of flow pathways causing increased surface water storage and, in some cases, the potential to change surface-groundwater exchanges with implications for local water table elevations on adjacent floodplains. Other effects may include reduced downstream peak discharge, and increased base flows. The importance of these processes at larger spatial scales (e.g. catchment scale) is largely not understood. Moreover, the growing number of beavers in the UK means that river managers will need to develop evidence-based management strategies for the hydrological changes caused by beaver dams. The principal aim of this thesis is to advance the understanding of how beaver dams affect stream flow and the hydrology of the adjacent floodplain at scales that range from an individual beaver dam to a small catchment (2.2 km2). The following research questions will be addressed: Research Question 1: What effect do beaver dams have on water level and stream discharge from the scale of an individual beaver dam to a small catchment? Research Question 2: What effect do beaver dams have on the hydrology of the adjacent floodplain from the scale of an individual beaver dam to catchment scale? Research Question 3: Can a pond leveller be an effective tool to reach a compromise in water level that is sufficient for beavers and also reduces the impact of beaver ponds on agricultural use of the adjacent floodplain?